LONDON, England (CNN) -- Nine of the 11 Pakistani nationals being held in an alleged terror plot in northern England were released Tuesday, according to police.

Police officers guard a house in Manchester, England, following raids and arrests of terror suspects.

The arrests were made the week before Easter and came quickly after Britain's chief terrorism officer, who has since resigned, exposed a list of people who were suspected of planning an al Qaeda-linked attack.

Britain's Greater Manchester Police said the men were released into the custody of the U.K.'s border agency, which will determine whether they can legally remain in England. Police and the border agency said they want the men deported, even though investigators apparently were unable to find enough evidence to charge them with crimes.

"We are seeking to remove these individuals on grounds of national security. The government's highest priority is to protect public safety," said a statement from the agency. "Where a foreign national poses a threat to this country, we will seek to exclude or to deport, where this is appropriate."

Twelve people originally were arrested April 8, and one had been released before Tuesday. Two people remained in custody, authorities said.

Police said that at the time of the arrests, their investigation compelled them to take action, even without the blunder made by Metropolitan Police Assistant Commissioner Bob Quick.

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The document he was carrying when photographed outside 10 Downing Street contained the names of those to be arrested, and a source said photographers were able to easily read the names when they enlarged the photographs.

Once the word was out, police rushed to make the arrests. Authorities said those actions would have been taken in the following 24 hours anyway.

The men -- ranging in age from 18 to 22 -- were arrested in Manchester, about 200 miles northwest of London. They had been held for 13 days without being charged. Police will need to seek an extension by Wednesday to be able to continue holding the two remaining suspects without charges.

Police say they are continuing to review evidence collected in the case and are searching at least one more house